Name the cell organelle which acts as 'protein factory' of the cell. Where is it located ?

Answer

**Step-by-step Solution:**

1. **Identify the Cell Organelle**: The cell organelle that acts as the 'protein factory' of the cell is called **ribosomes**. Ribosomes are essential for synthesizing proteins, which are crucial for various cellular functions.

2. **Function of Ribosomes**: Ribosomes are responsible for the process of **protein synthesis**. They translate messenger RNA (mRNA) into polypeptide chains, which then fold into functional proteins.

3. **Location of Ribosomes**: Ribosomes can be found in several locations within the cell:
- **Rough Endoplasmic Reticulum (RER)**: Ribosomes are often attached to the rough endoplasmic reticulum, giving it a "rough" appearance. This is a primary site for protein synthesis.
- **Free Ribosomes**: Ribosomes can also exist freely in the **cytoplasm**, where they synthesize proteins that function within the cytosol.
- **Mitochondria**: In plant cells, ribosomes are also present in mitochondria, which are involved in energy production and have their own ribosomes for synthesizing some of their proteins.

4. **Conclusion**: Therefore, the organelle that acts as the 'protein factory' is **ribosomes**, and they are located in the rough endoplasmic reticulum, freely in the cytoplasm, and in mitochondria.

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